Thermo-electric fire-alarm.



G. BLAGKHALL. THERMO ELECTRIC FIRE ALARM.

APPLICATION FILED MAR. 2, 1909. K Patented Apr. 5, 1910.

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GEORGE BLACKI-IALL, or 'ronon'ro, ONTARIO, CANADA.

THERMO-ELEGTRIC FIRE-ALARM.

Specification of Letters Patent.

Application filed March 2, 1969.

Patented Apr. 5, 1910.

Serial No. 480,898.

To all whom it may concern:

Be it known that I, GEORGE BLAOKHALL, a subject of the King of GreatBritain, and a resident of Toronto, in the Province of Ontario andDominion of Canada, have invented a new and Improved Thermo-ElectricFire-Alarm, of which the following is a full, clear, and exactdescription.

This invention relates to fire alarms, and is especially useful inbuildings, such as factories or warehouses, for the purpose of giving analarm in case of fire. It is also intended to be used in the holds ofships or in other situations where a local rise in temperature may beutilized to indicate the existence of a fire.

The invention consists in the construction and combination of parts,'tobe more fully disclosed hereinafter and particularly set forth in theclaims.

Reference is to'be had to the accompanying drawings forming a part ofthis specification, in which similar characters of reference indicatecorresponding parts in all the views, and in which Figure 1 is avertical section through a device constructed according to my invention,and showing the same as attached to a ceiling, this view being a sectionon the line 11 of Fig. 2; Fig. 2 is a bottom plan of the device; andFig. 3 is a vertical section through a terminal bulb, two of which areembodied in the device.

Referring more particularly to the parts, 1 represents a base platewhich is of circular form, having a depressed center 2 through whichscrews or other fastening devices 3 pass, which attach the plate to theceiling l. By reason of the depressed center, this base presents anannular boss 5, and upon this boss there is seated a dished cap or cover6. The base 1 and the cap 6 are of insulating material. The cap isattached to the base by means of fastening screws 7 passing throughconductor plates 8, which are arranged radially and project in to apoint near the center of the chamber 9, which is formed be tween thebase and the cap. The outer ends of these conductor plates projectbeyond the base, and are bent upwardly, so as to form angular seats orbinding posts 10 to receive the wires 11 of an electric circuit. Thesewires are clamped against the seat by means of binding screws 12, whichare mounted in binding plates 13 through which the aforesaid screws 7pass. The inner extremities of these plates 13 are provided with spurs14;, which engage the face of the dished cap and prevent the plates 13from moving out of alinement with the conductor plates. The lowerportion of the cap 6 is formed into a tubular central sleeve 15, whichprojects downwardly, as shown. Within this sleeve, there is received theneck 16 of a mercury-holder or bowl 17 This mercuryholder is in the formof a shell having a double wall so that a narrow sphericallycurved space18 is formed, in which mercury is placed. The double wall presents aconvex outer plate or wall and a concave inner wall or plate and theseplates conform to each other, as shown. In the space 9 within the bodyof the device are provided two terminal bulbs 19. The bodies 20 of thesebulbs are eggshaped and have elongated necks 21 which extend downwardlyinto the interior of the neck 16. In the space surrounding the necks 21,a suitable filler or packing material 22 is placed. At the upper ends ofthe bulbs 19, terminals 23 are attached by means of large fiat heads 24,which are exposed above the bulbs. These terminals 23 are in the form ofstems which extend down centrally into the necks 21. The terminal bulbsare placed in position so that the heads 2% are in engagement with theunder sides of the conductor plates 8.

hen the device is in operation, a suitable quantity of mercury is placedin the mercury-holder 17. On account of the peculiar construction of themercury-holder, it will be evident that a very large surface ispresented with respect to a relatively-small quantity of mercury.Furthermore, the form of the device is admirably adapted to concentratethe ascending currents of warm air which move toward the ceiling. thetemperature of the mercury-holder rises sutliciently by reason of a lirein the same room or locality, the mercury rises in the necks 21 of thebulbs 19 and forms a bridge between the terminals 23. In this way, anelectric circuit is closed, and an alarm will be given.

With the construction described, it will be evident that if the bowl ormercury-holder 17 should become broken, it can be replaced by removingthe cap (3 without disturbing any other parts of the device.

In the practical application of the invention the length of the terminalstems will be adapted for a predetermined temperature.

V hen F or instance, if the device is to be used in an engine room itmay be arranged to close the circuit at 150 to 200, though in anadjoining room, if desired, the length of the terminal stems may begreater so as to adapt the device to close the circuit at 100. Thisgives the device great utility and adaptability. In any particularsystem any number of different rooms or compartments could be wired soas to give an alarm at different temperatures, depending on the 10-cality at which the fire breaks out.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. A device of the class described having a mercury holder formed of apair of thin curved shells conforming to each other and disposed closetogether to form a retaining chamber for a thermo-sensitive liquid,presenting a great superficial area and a relatively small capacity,said holder having an upwardly projecting neck, a pair of ter minalbulbs having terminals with heads disposed at the upper ends of saidbulbs and having stems extending downwardly into said neck, andconductor plates in contact with said heads and adapted to conduct thecurrent therefrom.

2. A device of the class described, having a bowl for holding mercuryand having an upwardly-projecting neck, a cap having adownwardly-projecting sleeve receiving said neck, terminal bulbsdisposed above said cap and projecting downwardly into said neck, saidterminal bulbs having terminal stems extending downwardly into said neckand adapted to be bridged by the mercury, said terminal stems havingheads exposed at the upper ends of said bulbs, and conductor plates incontact respectively with said heads.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

GEORGE BLACKHALL.

Witnesses D. S. TovnLL, E. lllnnnnn.

